This invention relates to electric motors and the like and, more particularly, to an electric motor of the type having a pair of axially spaced sleeve bearings which are telescoped into a housing carried by a rotor and rotate on a stationary shaft projecting from a stator assembly. The bearings are made of porous material and are adapted to be permanently lubricated by an oil impregnated liner which is telescoped into the housing around the shaft and which is sandwiched between the opposing inboard faces of the bearings. Motors of this general type are disclosed in Lautner U.S. Pat. No. 2,904,709, in Anderson et al U.S. Pat. No. 3,626,221 and in Anderson, Jr. U.S. Pat. No. 3,763,386 and are commonly referred to as unit bearing motors.
The bearings of the motor disclosed in the '386 Patent are formed with angularly spaced passageways (e.g., slots or holes) which establish communication between the liner and the surface of the shaft. Oil seeping along the shaft accumulates in the passageways and is slung back to the liner by the centrifugal force generated by the rotating bearings. When the motor is idle, oil tends to accumulate in the passageways adjacent the shaft rather than bleeding out of the housing between the shaft and the bearings.
While the bearings of the '386 Patent are, in many respects, adequate from a functional standpoint, it is relatively expensive to form the angularly spaced slots or holes in the bearings. Milling of the slots is costly and, if the slots are molded in bearings of sintered bronze or the like, difficulty is encountered in releasing the die parts without distorting the slots or chipping the bearings. Moreover, the lubricating system of the motor of the '386 Patent is not completely sealed and thus, in certain instances, some oil leakage can occur and leave the bearings without sufficient lubrication.